The high-profile trial in Australia is in its final stages, with the defence and prosecution due to deliver their closing speeches to the jury next week.

Today, the final witnesses in the trial of Bradley Murdoch gave evidence in the Northern Territory Supreme Court in Darwin.

A body structure expert said Murdoch -accused of killing the Hepworth backpacker - had a different build to a man pictured in security footage just hours after the attack in the Australian Outback more than four years ago.

Prof Maciej Henneberg said Murdoch differed from the image of a man caught on CCTV footage at a truck stop in Alice Springs just hours after Mr Falconio was allegedly murdered and his girlfriend, Joanne Lees, abducted and assaulted near Barrow Creek on July 14, 2001.

Murdoch, 47, of Broome, Western Australia, denies all three charges.

Prof Henneberg, head of the anatomical science department at Adelaide University, said the man on the film was lean and medium to medium large in size.

Murdoch is 6ft 5in.

He added: "The person of interest in the CCTV image and Mr Murdoch differed in their body build and probably in their overall size and stature."

Mr Falconio and his girlfriend were allegedly attacked after being flagged down by another motorist at around 8pm on the Stuart Highway, about six miles north of Barrow Creek, which is to the north of Alice Springs.

Miss Lees, 32, of Brighton, told police she was threatened with a gun to her head, tied up with her hands behind her back and put in the back of her attacker's vehicle.

But she managed to escape from under the loose canopy.

Dr Katrin Both, a part-time forensic scientist at the Forensic Science Service in Adelaide, said she had "a large number of concerns" about tests which showed that a DNA sample on the handcuffs used to tie up Miss Lees was 100m times more likely to have come from Murdoch than anybody else.

She said her concerns centred on the reliability and interpretation of results found using a "low copy number" DNA technique by Dr Jonathan Whitaker, a senior forensic scientist with the UK's Forensic Science Service.

Dr Both said: "I think the method is very dangerous. He's pushing science to the limits."

But during cross-examination by Anthony Elliott, prosecuting, she admitted Dr Whitaker's results could have been independently verified, if defence counsel had chosen to.

She also admitted Dr Whitaker took steps to tackle the increased risk of contamination with the "low copy number" method.

Dr Both also said Dr Whitaker's "negative controls" in this case were clear, which she agreed suggested there were no spurious results.

Mr Falconio's father Luciano, laughed with other members of the public gallery as Prof Henneberg explained his work, using a series of anecdotes involving Eskimos and koala bears.

When the professor said they were, Mr Falconio's mother, Joan, and his brother, Nick, joined in the laughter during one of the lighter moments of the trial, which is now in its seventh week.

During cross-examination by Rex Wild QC, the Director of Public Prosecutors, the professor admitted that a prosecution witness, Dr Sutisno, had carried out further enhancement of the CCTV images, which he had not.

"She uses the same basic principles of comparing images feature by feature, so to that extent that's the same procedure. I used the original images. I never manipulate images that I receive."

Mr Wild said: "When it comes down to it she can see more than you and she had different methods in coming to the conclusions she did."

Prof Henneberg said: "Well, she may have been using the images differently."

Chief Justice Martin told the 15 jurors, the six men and six women who will try the case and three reserves: "The next stage is for counsel to address you. Then I will sum up."